What are Ensemble Streamflow Probabilistic (ESP) Forecasts?

The ESP system utilizes historical precipitation and temperature data as input along with the current river, snow and soil moisture conditions to the River Forecast Center's Hydrologic Model to produce long-range probabilistic forecasts. These long-range forecasts provide information on possible future river stage, flow and /or volume at river forecast points. Forecasts are generally for a 90-day period and are issued once a month. These are issued at the end of the month for the upcoming next three month period.

About The Analysis

A simple categorical verification has been conducted to determine the forecast quality of the probabilistic forecasts that are issued generally once a month. The analysis determines the observed exceedance percentage (OEP) for each location and forecast exceedance probability (FEP) category.

This is done as follows, for each location and FEP category:

1) find the max observed value for each 3-month forecast period

2) count the number of times the max observed value is ≥ forecast value for each FEP category